Ultrasonic identification tags are used to mark, inventory and track various items. Ultrasonic identification tags generally modulate and transmit data ultrasonically, and the data may include, for example, a serial number or product information. An ultrasonic reader may then receive and demodulate the data, determining a presence of the items.
Ultrasonic signals are generally poor at permeating sound absorbing or reflecting barriers such as walls. Therefore, the signal to noise ratio of data transmitted from a tag may be reduced by the environment between the tag and a reader. For example, layers of sound absorbent and/or reflective material, such as soft fabrics or thermal insulation, may attenuate the sound pressure level or loudness of the ultrasonic sound wave. As the signal to noise ratio increases, the likelihood of mishearing or not hearing a tag increases.
Additionally, as ultrasonic signals are generally poor at permeating sound absorbing or reflecting barriers, such as walls, a large number of sensors are often required for accurate locationing of tags.
Accordingly, there is a need for an improved method and apparatus for ultrasonic data transmission and/or locationing.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.